Speed-constrained flight management methods and systems

ABSTRACT

Systems and methods are provided for managing speed-constrained vehicle operations. One exemplary method of operating an aircraft involves identifying a speed constraint associated with a navigational reference point, determining a speed envelope region en route to the navigational reference point based at least in part on the first speed constraint, identifying a target speed en route to the navigational reference point, and determining a speed profile for autonomously operations en route to the navigational reference point within the speed envelope region. The speed profile intersects the target speed within the speed envelope region and a slope of the speed profile is influenced by the target speed, for example, to effectuate or approximate the target speed by increasing the duration of time operation at or around the target speed is achieved. In one or more embodiments, multiple different target speeds associated with different flight levels or operating regions are accounted for.

TECHNICAL FIELD

The subject matter described herein relates generally to vehiclesystems, and more particularly, embodiments of the subject matter relateto managing aircraft operations in connection with speed constraints.

BACKGROUND

In order to handle the expected increases in air traffic and congestion,the Next Generation Air Transportation System (NextGen) will introduceaircraft trajectory-based operations that require aircraft to followcustom-made so-called four-dimensional (4D) trajectories consisting of aspecified path along-path time conformance requirements. This promotesprescribing and accurately following trajectories that ensure separationand optimize traffic flow management over different time horizons, whichwill significantly improve flight safety and performance. Thus, requiredtime of arrival (RTA) and speed constraints are introduced to helpguarantee the reliability of time of arrival at a particular waypoint tomanage spacing between aircraft, minimize delays, and the like.

However, the RTA constraints, speed constraints and other altitude-basedspeed restrictions that may be provided by airport procedures, airtraffic control (ATC), or the like typically do not account foroperating costs. For example, the particular cost function utilized by aparticular aircraft operator may define an optimum speed for achieving adesired cost index given the particular altitude of the aircraft andpotentially other factors (e.g., the current fuel remaining or aircraftweight, current meteorological conditions, and the like). Accordingly,it is desirable to provide a system and method for managing speedconstraints or other constraints pertaining to temporal operations in amanner that accounts for operating costs. Other desirable features andcharacteristics will become apparent from the subsequent detaileddescription and the appended claims, taken in conjunction with theaccompanying drawings and the foregoing technical field and background.

BRIEF SUMMARY

Vehicle systems and related operating methods are provided. In oneembodiment, a computer-implemented method of operating a vehicle isprovided. The method involves identifying a first speed constraintassociated with a navigational reference point, determining a speedenvelope region en route to the navigational reference point based atleast in part on the first speed constraint and a maximum accelerationof the vehicle, identifying a target speed en route to the navigationalreference point, and determining a speed profile for travel en route tothe navigational reference point within the speed envelope region. Thespeed profile intersects the target speed within the speed enveloperegion and a slope of the speed profile is influenced by the targetspeed, and the vehicle is autonomously operated in accordance with thespeed profile.

In another embodiment, a method of operating an aircraft is provided.The method involves a flight management system (FMS) onboard theaircraft identifying one of an AT speed constraint and an AT OR ABOVEspeed constraint associated with a navigational reference point of aflight plan, determining a speed envelope region in advance of thenavigational reference point based at least in part on a maximumacceleration of the aircraft and the one of the AT speed constraint andthe AT OR ABOVE speed constraint, identifying a target speed en route tothe navigational reference point, and determining a speed profile thatintersects the target speed within the speed envelope region. A slope ofthe speed profile is influenced by the target speed, and the aircraft isautonomously operated in accordance with the speed profile.

An embodiment of an aircraft system is also provided. The aircraftsystem includes a data storage element maintaining procedure informationassociated with an aircraft action, wherein the procedure informationincludes a navigational reference point having a speed constraintassociated therewith, an input device to receive an input value, and aprocessing system coupled to the data storage element and the inputdevice to determine a speed envelope region en route to the navigationalreference point based at least in part on the speed constraint, identifya target speed corresponding to the input value, determine a speedprofile intersecting the target speed within the speed envelope region,and autonomously operating an aircraft in accordance with the speedprofile, wherein a slope of the speed profile is influenced by thetarget speed.

Furthermore, other desirable features and characteristics of the subjectmatter described herein will become apparent from the subsequentdetailed description and the appended claims, taken in conjunction withthe accompanying drawings and the preceding background.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following figures, wherein like numerals denote like elements, andwherein:

FIG. 1 is a block diagram illustrating an aircraft system in accordancewith one or more exemplary embodiments;

FIG. 2 is a flow diagram illustrating a speed profile determinationprocess suitable for implementation by the aircraft system of FIG. 1 inaccordance with one or more exemplary embodiments;

FIGS. 3-4 are graphs depicting exemplary speed profiles with respect toflight level that may be generated by the speed profile determinationprocess in accordance with one or more exemplary embodiments;

FIG. 5 is a graph depicted an exemplary speed profile with respect toflight level that may be generated by the speed profile determinationprocess using padded speed constraints in accordance with one or moreexemplary embodiments; and

FIG. 6 is a block diagram of a required time of arrival (RTA) managementsystem suitable for implementation with the speed profile determinationprocess of FIG. 2 in accordance with one or more exemplary embodiments.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the subject matter of the application and usesthereof. Furthermore, there is no intention to be bound by any theorypresented in the preceding background, brief summary, or the followingdetailed description.

Embodiments of the subject matter described herein relate to vehiclemanagement systems and methods for determining a travel profile forautonomous operations in a manner that accounts for travel constraintsassociated with points within a travel plan as well as cost indextargets or desired travel targets within the travel plan. For purposesof explanation, the subject matter is primarily described herein in thecontext of aircraft flight management systems and methods fordetermining a speed profile for autonomously operating an aircraft enroute to a speed constrained navigational reference point of a flightplan in a manner that accounts for the speed constraints associated withthat en route reference point as well as a desired (or targeted) speed,such as a speed based on a desired cost index, cost function, or otheroptimization criteria. That said, the subject matter described herein isnot necessarily limited to aircraft or avionic environments, and inalternative embodiments, may be implemented in an equivalent manner inthe context of other types of vehicles and travel plans.

As described in greater detail below in the context of FIGS. 2-3, inexemplary embodiments, a speed envelope region of potential aircraftspeeds in advance of a navigational reference point is calculated,determined, or otherwise defined based on the speed constraintassociated with the navigational reference point and any other speedconstraints in advance of reaching the navigational reference point,such as, for example, a current aircraft speed, speed constraintsassociated with a preceding navigational reference point, speedconstraints associated with travel en route to the navigationalreference point, and the like. A boundary of the speed envelope regioncorresponding to a minimum amount of travel time for reaching thenavigational reference point may be calculated or otherwise determinedbased on the speed constraint associated with the navigational referencepoint, any maximum aircraft speed constraints en route to thenavigational reference point, and the maximum acceleration of theaircraft. Another boundary of the speed envelope region corresponding toa maximum amount of travel time for reaching the navigational referencepoint may be calculated or otherwise determined based on the speedconstraint associated with the navigational reference point, any minimumaircraft speed constraints en route to the navigational reference point,and the maximum acceleration of the aircraft.

Once a speed envelope region in advance of a navigational referencepoint is defined, one or more desired aircraft speed targets associatedwith travel in advance of the navigational reference point areidentified and utilized to construct or otherwise determine a speedprofile that intersects those targeted aircraft speeds within the speedenvelope region. The speed profile is then utilized to autonomouslyoperate the aircraft and regulate the aircraft's speed when traveling enroute to the navigational reference point.

In accordance with one or more embodiments, the speed profile iscalculated or otherwise determined to maximize the duration of timeduring which the aircraft travels at the targeted speed(s) while enroute to the navigational reference point, as described in greaterdetail below in the context of FIG. 3. In this manner, the amount oftime during which the aircraft operates at or near a desired or optimumcost can be maximized while maintaining compliance with other speedconstraints. In other embodiments, the speed profile is calculated orotherwise determined to maximize the duration of time during which theaverage aircraft speed while en route to the navigational referencepoint is equal to the desired speed(s), as described in greater detailbelow in the context of FIG. 4. Additionally, in some embodiments, thespeed constraints associated with a navigational reference point may bepadded in a manner that increases the area of the speed envelope regionto increase the duration of time during which the aircraft can operateat or average the targeted speed(s) within the speed envelope region, asdescribed in greater detail below in the context of FIG. 5. In someembodiments, the speed profile may be iteratively determined inconjunction with required time of arrival (RTA) constraints, asdescribed in greater detail below in the context of FIG. 6.

For purposes of explanation, but without limitation, the subject mattermay be described herein primarily in the context of a flight managementsystem (FMS) climb speed profile that may be utilized by the autopilotor other automated functionality provided by an FMS to autonomouslymanage the climb speed of an aircraft during execution of a departureprocedure. In this regard, navigational reference points of a departureprocedure may be associated with speed constraints requiring aparticular aircraft speed to maintain desired separation of aircraftdeparting from an airport, such as, for example, AT constraints or AT ORABOVE constraints, which require an aircraft to be traveling at or abovea particular speed upon reaching that particular navigational referencepoint. These constraints may be part of a published or standardizeddeparture procedure, or alternatively, provided by air traffic control(ATC) based on current operations at the airport. The navigationalreference points of the departure procedure may be associated with aparticular altitude at which the aircraft is required to be at or aboveduring execution of the departure. A cost function may be utilized toidentify desired speeds at different altitudes or flight levels withinthe departure at which the aircraft operates at or best achieves adesired cost index value. Accordingly, the subject matter describedherein may be utilize to satisfy AT, AT OR ABOVE, or AT OR BELOW speedconstraints while also accounting for operating costs to achieve morecost-efficient operations during an automated departure or climbingphase of flight. That said, the subject matter described herein is notlimited to departures or climbs, and may be utilized in an equivalentmanner for other aircraft procedures or flight phases, such as, forexample, descents, approaches, and the like.

FIG. 1 depicts an exemplary embodiment of a system 100 which may beutilized with a vehicle, such as an aircraft 120. In an exemplaryembodiment, the system 100 includes, without limitation, a displaydevice 102, a user input device 104, a processing system 106, a displaysystem 108, a communications system 110, a navigation system 112, aflight management system (FMS) 114, one or more avionics systems 116,and a data storage element 118 suitably configured to support operationof the system 100, as described in greater detail below.

In exemplary embodiments, the display device 102 is realized as anelectronic display capable of graphically displaying flight informationor other data associated with operation of the aircraft 120 undercontrol of the display system 108 and/or processing system 106. In thisregard, the display device 102 is coupled to the display system 108 andthe processing system 106, wherein the processing system 106 and thedisplay system 108 are cooperatively configured to display, render, orotherwise convey one or more graphical representations or imagesassociated with operation of the aircraft 120 on the display device 102.The user input device 104 is coupled to the processing system 106, andthe user input device 104 and the processing system 106 arecooperatively configured to allow a user (e.g., a pilot, co-pilot, orcrew member) to interact with the display device 102 and/or otherelements of the system 100, as described in greater detail below.Depending on the embodiment, the user input device 104 may be realizedas a keypad, touchpad, keyboard, mouse, touch panel (or touchscreen),joystick, knob, line select key or another suitable device adapted toreceive input from a user. In some embodiments, the user input device104 is realized as an audio input device, such as a microphone, audiotransducer, audio sensor, or the like, that is adapted to allow a userto provide audio input to the system 100 in a “hands free” mannerwithout requiring the user to move his or her hands, eyes and/or head tointeract with the system 100.

The processing system 106 generally represents the hardware, software,and/or firmware components configured to facilitate communicationsand/or interaction between the elements of the system 100 and performadditional tasks and/or functions to support operation of the system100, as described in greater detail below. Depending on the embodiment,the processing system 106 may be implemented or realized with a generalpurpose processor, a content addressable memory, a digital signalprocessor, an application specific integrated circuit, a fieldprogrammable gate array, any suitable programmable logic device,discrete gate or transistor logic, processing core, discrete hardwarecomponents, or any combination thereof, designed to perform thefunctions described herein. The processing system 106 may also beimplemented as a combination of computing devices, e.g., a plurality ofprocessing cores, a combination of a digital signal processor and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a digital signal processor core, orany other such configuration. In practice, the processing system 106includes processing logic that may be configured to carry out thefunctions, techniques, and processing tasks associated with theoperation of the system 100, as described in greater detail below.Furthermore, the steps of a method or algorithm described in connectionwith the embodiments disclosed herein may be embodied directly inhardware, in firmware, in a software module executed by the processingsystem 106, or in any practical combination thereof. For example, in oneor more embodiments, the processing system 106 includes or otherwiseaccesses a data storage element (or memory), which may be realized asany sort of non-transitory short or long term storage media capable ofstoring programming instructions for execution by the processing system106. The code or other computer-executable programming instructions,when read and executed by the processing system 106, cause theprocessing system 106 to support or otherwise perform certain tasks,operations, functions, and/or processes described herein.

The display system 108 generally represents the hardware, software,and/or firmware components configured to control the display and/orrendering of one or more navigational maps and/or other displayspertaining to operation of the aircraft 120 and/or onboard systems 110,112, 114, 116 on the display device 102. In this regard, the displaysystem 108 may access or include one or more databases suitablyconfigured to support operations of the display system 108, such as, forexample, a terrain database, an obstacle database, a navigationaldatabase, a geopolitical database, a terminal airspace database, aspecial use airspace database, or other information for rendering and/ordisplaying navigational maps and/or other content on the display device102.

In exemplary embodiments, the aircraft system 100 includes a datastorage element 118, which contains aircraft procedure information (orinstrument procedure information) for a plurality of airports andmaintains association between the aircraft procedure information and thecorresponding airports. Depending on the embodiment, the data storageelement 118 may be physically realized using RAM memory, ROM memory,flash memory, registers, a hard disk, or another suitable data storagemedium known in the art or any suitable combination thereof.

As used herein, aircraft procedure information should be understood as aset of operating parameters, constraints, or instructions associatedwith a particular aircraft action (e.g., approach, departure, arrival,climbing, and the like) that may be undertaken by the aircraft 120 at orin the vicinity of a particular airport. As used herein, an airportshould be understood as referring to a location suitable for landing (orarrival) and/or takeoff (or departure) of an aircraft, such as, forexample, airports, runways, landing strips, and other suitable landingand/or departure locations, and an aircraft action should be understoodas referring to an approach (or landing), an arrival, a departure (ortakeoff), an ascent, taxiing, or another aircraft action havingassociated aircraft procedure information. Each airport may have one ormore predefined aircraft procedures associated therewith, wherein theaircraft procedure information for each aircraft procedure at eachrespective airport may be maintained by the data storage element 118.The aircraft procedure information may be provided by or otherwiseobtained from a governmental or regulatory organization, such as, forexample, the Federal Aviation Administration in the United States. In anexemplary embodiment, the aircraft procedure information comprisesinstrument procedure information, such as instrument approachprocedures, standard terminal arrival routes, instrument departureprocedures, standard instrument departure routes, obstacle departureprocedures, or the like, traditionally displayed on a published charts,such as Instrument Approach Procedure (IAP) charts, Standard TerminalArrival (STAR) charts or Terminal Arrival Area (TAA) charts, StandardInstrument Departure (SID) routes, Departure Procedures (DP), terminalprocedures, approach plates, and the like. In exemplary embodiments, thedata storage element 118 maintains associations between prescribedoperating parameters, constraints, and the like and respectivenavigational reference points (e.g., waypoints, positional fixes, radioground stations (VORs, VORTACs, TACANs, and the like), distancemeasuring equipment, non-directional beacons, or the like) defining theaircraft procedure, such as, for example, altitude minima or maxima,minimum and/or maximum speed constraints, RTA constraints, and the like.It should be noted that although the subject matter is described belowin the context of departure procedures and/or climbing procedures forpurposes of explanation, the subject matter is not intended to belimited to use with any particular type of aircraft procedure and may beimplemented for other aircraft procedures (e.g., approach procedures oren route procedures) in an equivalent manner.

Still referring to FIG. 1, in an exemplary embodiment, the processingsystem 106 is coupled to the navigation system 112, which is configuredto provide real-time navigational data and/or information regardingoperation of the aircraft 120. The navigation system 112 may be realizedas a global positioning system (GPS), inertial reference system (IRS),or a radio-based navigation system (e.g., VHF omni-directional radiorange (VOR) or long range aid to navigation (LORAN)), and may includeone or more navigational radios or other sensors suitably configured tosupport operation of the navigation system 112, as will be appreciatedin the art. The navigation system 112 is capable of obtaining and/ordetermining the instantaneous position of the aircraft 120, that is, thecurrent (or instantaneous) location of the aircraft 120 (e.g., thecurrent latitude and longitude) and the current (or instantaneous)altitude or above ground level for the aircraft 120. The navigationsystem 112 is also capable of obtaining or otherwise determining theheading of the aircraft 120 (i.e., the direction the aircraft istraveling in relative to some reference). In the illustrated embodiment,the processing system 106 is also coupled to the communications system110, which is configured to support communications to and/or from theaircraft 120. For example, the communications system 110 may supportcommunications between the aircraft 120 and air traffic control oranother suitable command center or ground location. In this regard, thecommunications system 110 may be realized using a radio communicationsystem or another suitable data link system.

In an exemplary embodiment, the processing system 106 is also coupled tothe FMS 114, which is coupled to the navigation system 112, thecommunications system 110, and one or more additional avionics systems116 to support navigation, flight planning, and other aircraft controlfunctions in a conventional manner, as well as to provide real-time dataand/or information regarding the operational status of the aircraft 120to the processing system 106. Although FIG. 1 depicts a single avionicssystem 116, in practice, the system 100 and/or aircraft 120 will likelyinclude numerous avionics systems for obtaining and/or providingreal-time flight-related information that may be displayed on thedisplay device 102 or otherwise provided to a user (e.g., a pilot, aco-pilot, or crew member). For example, practical embodiments of thesystem 100 and/or aircraft 120 will likely include one or more of thefollowing avionics systems suitably configured to support operation ofthe aircraft 120: a weather system, an air traffic management system, aradar system, a traffic avoidance system, an autopilot system, anautothrust system, a flight control system, hydraulics systems,pneumatics systems, environmental systems, electrical systems, enginesystems, trim systems, lighting systems, crew alerting systems,electronic checklist systems, an electronic flight bag and/or anothersuitable avionics system.

It should be understood that FIG. 1 is a simplified representation ofthe system 100 for purposes of explanation and ease of description, andFIG. 1 is not intended to limit the application or scope of the subjectmatter described herein in any way. It should be appreciated thatalthough FIG. 1 shows the display device 102, the user input device 104,and the processing system 106 as being located onboard the aircraft 120(e.g., in the cockpit), in practice, one or more of the display device102, the user input device 104, and/or the processing system 106 may belocated outside the aircraft 120 (e.g., on the ground as part of an airtraffic control center or another command center) and communicativelycoupled to the remaining elements of the system 100 (e.g., via a datalink and/or communications system 110). Similarly, in some embodiments,the data storage element 118 may be located outside the aircraft 120 andcommunicatively coupled to the processing system 106 via a data linkand/or communications system 110. Furthermore, practical embodiments ofthe system 100 and/or aircraft 120 will include numerous other devicesand components for providing additional functions and features, as willbe appreciated in the art. In this regard, it will be appreciated thatalthough FIG. 1 shows a single display device 102, in practice,additional display devices may be present onboard the aircraft 120.Additionally, it should be noted that in other embodiments, featuresand/or functionality of processing system 106 described herein can beimplemented by or otherwise integrated with the features and/orfunctionality provided by the FMS 114. In other words, some embodimentsmay integrate the processing system 106 with the FMS 114. In yet otherembodiments, various aspects of the subject matter described herein maybe implemented by or at an electronic flight bag (EFB) or similarelectronic device that is communicatively coupled to the processingsystem 106 and/or the FMS 114.

Referring now to FIG. 2, in an exemplary embodiment, an aircraft systemis configured to support a speed profile determination process 200 andperform additional tasks, functions, and operations described below. Thevarious tasks performed in connection with the illustrated process 200may be implemented using hardware, firmware, software executed byprocessing circuitry, or any combination thereof. For illustrativepurposes, the following description may refer to elements mentionedabove in connection with FIG. 1. In practice, portions of the speedprofile determination process 200 may be performed by different elementsof the aircraft system 100. That said, exemplary embodiments aredescribed herein in the context of the speed profile determinationprocess 200 being primarily performed by the processing system 106and/or FMS 114. It should be appreciated that the speed profiledetermination process 200 may include any number of additional oralternative tasks, the tasks need not be performed in the illustratedorder and/or the tasks may be performed concurrently, and/or the speedprofile determination process 200 may be incorporated into a morecomprehensive procedure or process having additional functionality notdescribed in detail herein. Moreover, one or more of the tasks shown anddescribed in the context of FIG. 2 could be omitted from a practicalembodiment of the speed profile determination process 200 as long as theintended overall functionality remains intact.

For purposes of explanation, the speed profile determination process 200is described primarily in the context of determining a speed profileoptimizing climb speeds for a departure procedure or climbing phase offlight, however, it should be appreciated that the subject matterdescribed herein is not limited to any particular type of procedure orphase of flight. Additionally, for ease of explanation, the speedprofile determination process 200 may be described initially in thecontext of an individual navigational segment; however, as described ingreater detail below, in one or more embodiments, the speed profiledetermination process 200 is iteratively performed across multiplenavigational segments of a procedure to cumulatively optimize a speedprofile (e.g., maximizing cumulative duration of time spent at oraveraging cost-indexed speed targets across an entire procedure) ratherthan optimizing the speed profile in a piecewise manner (e.g.,maximizing duration of time spent at or averaging cost-indexed speedtargets within individual navigational segments). Additionally, thespeed profile determination process 200 can be periodically and/orcontinually performed throughout execution of a procedure to dynamicallyupdate the speed profile to account for the current speed or status ofthe aircraft.

Referring to FIG. 2, and with continued reference to FIG. 1, theillustrated speed profile determination process 200 begins by receiving,obtaining or otherwise identifying the speed constraint associated withthe destination or en route navigational reference point of anavigational segment (task 202). In this regard, the processing system106 and/or the FMS 114 identifies the value (or airspeed) associatedwith the en route waypoint defining the end of a navigational segmentand the type of speed constraint associated with that waypoint (e.g.,whether the constraint is an AT constraint, an AT OR ABOVE speedconstraint, or an AT OR BELOW speed constraint). Depending on theembodiment, the en route waypoint speed constraint may be identified orobtained from the procedure information stored in the data storageelement 118, from ATC (e.g., via communications system 110), or from apilot or other user (e.g., via user input device 104).

Additionally, the speed profile determination process 200 receives,obtains or otherwise identifies the speed constraint associated with thestart of the navigational segment en route to that speed-constrainednavigational reference point (task 204). Similar to the en routewaypoint, the processing system 106 and/or the FMS 114 identifies thevalue (or airspeed) associated with the preceding waypoint defining thestart of the navigational segment of interest and the type of speedconstraint associated with that waypoint (e.g., whether the constraintis an AT constraint, an AT OR ABOVE speed constraint, or an AT OR BELOWspeed constraint). Again, depending on the embodiment, the precedingwaypoint speed constraint may be identified or obtained from theprocedure information stored in the data storage element 118, from ATC,or from a pilot or other user. If the preceding waypoint does not havean associated speed constraint, the processing system 106 and/or the FMS114 may identify the current or anticipated airspeed at that precedingwaypoint as the speed constraint associated with the start of thenavigational segment.

The speed profile determination process 200 also receives, obtains orotherwise identifies the speed constraints associated with traversingthe navigational segment en route to the speed-constrained navigationalreference point (task 206). In this regard, the processing system 106and/or the FMS 114 identifies any minimum or maximum airspeed values forthe period of travel en route to the speed-constrained waypoint. Again,depending on the embodiment, the preceding waypoint speed constraint maybe identified or obtained from the procedure information stored in thedata storage element 118, from ATC, or from a pilot or other user. Insome embodiments, the minimum or maximum airspeed values may bedetermined based on aircraft capabilities, and may be calculated inreal-time based on the predicted aircraft weight, altitude, airspeed,meteorological conditions, and/or other factors while en route to thewaypoint.

After identifying speed constraints associated with traveling anavigational segment from a starting location to a speed-constrainednavigational reference point, the speed profile determination process200 calculates or otherwise determines a speed envelope region that isbounded by one or more of the speed constraints (task 208). In thisregard, in one or more exemplary embodiments, the speed envelope regionrepresents the potential range of airspeeds achievable by the aircraft(e.g., based on the maximum aircraft acceleration/decelerationcapabilities) at various locations along the navigational segment enroute to the speed-constrained waypoint without violating the speedconstraints. That said, as described in greater detail below in thecontext of FIG. 5, in some embodiments, the speed constraints associatedwith one or more waypoints may be padded or loosened, such that thespeed envelope region represents the potential range of airspeedsachievable by the aircraft without violating the speed constraintsassociated with the endpoints of a navigational segment by more than athreshold amount.

In exemplary embodiments, the processing system 106 and/or the FMS 114determines the speed envelope region by calculating or otherwisedetermining a first boundary corresponding to the minimum amount oftravel time for traversing the navigational segment en route to thespeed-constrained waypoint and an opposing boundary corresponding to themaximum amount of travel time for traversing the navigational segment.The minimum travel time boundary generally starts from a maximumallowable or achievable speed value at the initial reference pointdefining the navigational segment and assumes a maximum acceleration ofthe aircraft until reaching any maximum airspeed constraints andtraveling at those maximum airspeeds for a maximum duration of timeuntil reaching the speed-constrained waypoint with a maximum airspeedthat satisfies the waypoint's associated speed constraint. In thisregard, if any maximum airspeed constraint exceeds the waypoint'sassociated speed constraint, the minimum travel time boundary may assumea maximum deceleration from such maximum airspeed values down to thewaypoint's associated speed constraint or other subsequent speedconstraints. Conversely, the maximum travel time boundary generallystarts from a minimum allowable or achievable speed value at the initialreference point defining the navigational segment maximizes the durationof travel at the minimum airspeed until accelerating at the maximumacceleration of the aircraft until reaching the next minimum airspeedconstraint en route to or at the speed-constrained waypoint.

FIG. 3 depicts a graph 300 of airspeeds with respect to flight level foran exemplary climb speed profile associated with a departure procedure.With reference to FIGS. 1-2, FIG. 3 depicts a speed envelope region 302that may be determined by the processing system 106 and/or the FMS 114for climbing from an initial AT OR BELOW speed constraint 306 (e.g., ATOR BELOW 250 knots) associated with a start of a navigational segment toan AT speed constraint 304 (e.g., AT 270 knots) associated with awaypoint defining the end of the navigational segment. In this regard,the processing system 106 and/or the FMS 114 calculates a minimum traveltime boundary 301 for the speed envelope region 302 that starts at themaximum airspeed that satisfies the speed constraint associated with theinitial waypoint of the navigational segment (e.g., the value for the ATOR BELOW speed constraint 306) and accelerates at the maximumacceleration of the aircraft while en route between waypoints (which maybe determined based on predicted aircraft weight, altitude level,meteorological conditions, engine status, and/or potentially otherfactors) before reaching a maximum airspeed constraint 308 associatedwith travel en route to the waypoint at the end of the navigationalsegment, and then maximizing the duration of time traveled at themaximum airspeed constraint 308 before arriving at the maximum airspeedat the en route waypoint that satisfies its associated constraint (e.g.,the value for the AT speed constraint 304). Conversely, the maximumtravel time boundary 303 for the speed envelope region 302 may start atthe minimum airspeed that satisfies the initial waypoint speedconstraint 306 and/or the minimum airspeed constraint 310 associatedwith travel within the navigational segment for the maximum duration oftime that allows the airspeed to satisfy the en route waypoint speedconstraint 304 given the maximum acceleration of the aircraft while enroute.

Similarly, the processing system 106 and/or the FMS 114 may determine asubsequent speed envelope region 312 for climbing from the AT speedconstraint 304 to the next successive waypoint having an associated ATOR ABOVE speed constraint 314 (e.g., AT OR ABOVE 290 knots). The minimumtravel time boundary 311 for the speed envelope region 312 that startsat the maximum airspeed satisfying the initial constraint 304 (e.g., thevalue for the AT speed constraint 304) and accelerates at the maximumacceleration of the aircraft while en route until reaching a maximumairspeed constraint 318 associated with that navigational segment, andthen maximizing the duration of time traveled at the maximum airspeedconstraint 308 before arriving at the maximum airspeed at the en routewaypoint that satisfies the AT OR ABOVE speed constraint 314 (which isequal to the maximum airspeed constraint 318). The maximum travel timeboundary 313 for the speed envelope region 312 starts at the minimumairspeed that satisfies the initial speed constraint 304 (e.g., thevalue of the AT speed constraint 304) and then attempts to travel at theminimum speed constraint 320 associated with the navigational segmentfor the maximum duration of time that allows the airspeed to satisfy thevalue of the AT OR ABOVE speed constraint 314 upon reaching thatwaypoint at the end of the segment given the maximum accelerationcapability of the aircraft.

Referring again to FIG. 2, after determining a speed envelope region fora particular navigational segment, the speed profile determinationprocess 200 receives, obtains or otherwise identifies any desired ortarget airspeeds relevant to the navigational segment and thenconstructs or otherwise determines a speed profile within the speedenvelope region that intersects the targeted speed(s) (tasks 210, 212).In an exemplary embodiment, the targeted airspeeds are calculated orotherwise determined by the processing system 106 and/or the FMS 114 atparticular flight levels or altitudes based on an input cost index valueand current or predicted aircraft status information. For example, apilot or other user may utilize the user input device 104 to provide adesired cost index value, which, in turn, is utilized by the processingsystem 106 and/or the FMS 114 to determine a targeted airspeed (oroptimum speed) associated with a particular flight level (or rangethereof) that achieves the input cost index value based on a variety offactors, as will be understood to those skilled in the art and thedetails of which are not germane to the subject matter described herein.That said, in other embodiments, a pilot or other user may utilize theuser input device 104 to input or otherwise provide desired airspeedsfor use at particular flight levels in lieu of or in addition to thosedetermined using a cost index value or cost function.

Once the target airspeed(s) for a navigational segment are identified,the processing system 106 and/or the FMS 114 constructs a speed profilewithin the speed envelope region for that navigational segment thatintersects the targeted airspeed(s). In one or more exemplaryembodiments, the processing system 106 and/or the FMS 114 constructs aspeed profile that maximizes an amount of travel at a targeted airspeedwithin the navigational segment, as illustrated in FIG. 3. Inalternative embodiments, the processing system 106 and/or the FMS 114constructs a speed profile that maximizes an amount of travel over whichthe average airspeed is equal to a targeted airspeed, as illustrated inFIG. 4.

Referring first to FIG. 3, based on the input cost index value, theprocessing system 106 and/or the FMS 114 calculates or otherwisedetermines a first target airspeed (or optimum climb speed) up toreaching flight level 100 (FL100) equal to OPT CLB SPD 1, a secondtarget airspeed up to reaching FL150 equal to OPT CLB SPD 2, a thirdtarget airspeed up to reaching FL200 equal to OPT CLB SPD 3, and afourth target airspeed up to reaching FL250 equal to OPT CLB SPD 4. Forthe first navigational segment for climbing from the AT OR BELOW speedconstraint 306 to the AT speed constraint 304, the processing system 106and/or the FMS 114 constructs a speed profile 350 within the speedenvelope region 302 that has a combination of differently slopedportions configured to maximize the duration of time at which theairspeed is equal to either OPT CLB SPD 1 or OPT CLB SPD 2. Inparticular, the processing system 106 and/or the FMS 114 may constructthe speed profile 350 to maximize the duration of time the airspeed isequal to OPT CLB SPD 1 until the aircraft altitude is expected to reachFL100, and then increase with a slope corresponding to a maximumallowable acceleration of the aircraft until reaching OPT CLB SPD 2 tomaximize the duration of time the airspeed is equal to OPT CLB SPD 2before the aircraft altitude reaches FL150, and then increase with aslope corresponding to the maximum acceleration to satisfy the AT speedconstraint 304. In this regard, if the constructed profile 350 were toreach the maximum travel time boundary 303 prior to FL150 (e.g., due toa higher value for the AT speed constraint 304), the speed profile 350would begin accelerating at the maximum acceleration prior to reachingFL150 to ensure the AT constraint 304 is satisfied. For the followingsegment between the AT constraint 304 and the AT OR ABOVE constraint314, the processing system 106 and/or the FMS 114 constructs a speedprofile 360 within the speed envelope region 312 that accelerates withthe maximum acceleration along the minimum travel time boundary 311until reaching the targeted airspeed up to FL200 and then remains at OPTCLB SPD 3 until reaching FL200 and then accelerating with the maximumacceleration until reaching the next targeted airspeed (OPT CLB SPD 4)and then maximizing the duration of time at that target value.

Referring to FIGS. 2-3, it should be noted that the speed profiledetermination process 200 allows for maximizing the total amount offlight time spent at one of the multiple different optimum climb speedscalculated by the FMS 114 for multiple different flight levels oroperating regions. Thus, a climb, descent, or other procedure may besubdivided into any number of regions or segments, which, in turn, couldeach be associated with a particular optimum speed associated therewith,with the speed profile determination process 200 being utilized tomaximize the cumulative amount of time the aircraft is flying at one ofthe optimum speeds within the respective operating regions or segments.

FIG. 4 depicts an alternative embodiment for constructing speed profiles402, 404 within speed envelope regions 302, 312. In this regard, FIG. 4depicts a graph 400 where the constructed speed profile attempts tomaximize the duration of time when the aircraft is continuouslyaccelerating during a climb to achieve a smoother climb. For speedenvelope region 302, rather than maximizing a duration of time that theairspeed is equal to OPT CLB SPD 2, speed profile 402 is constructed tomaximize a duration of time over which the average airspeed is equal toOPT CLB SPD 2 by including a linearly sloped portion 403 having anaverage value equal to OPT CLB SPD 2. The linearly sloped portion 403intersects OPT CLB SPD 2 at its associated flight level (FL150), and theslope of the portion 403 is minimized to maximize the duration of timethe average value is equal to OPT CLB SPD 2. In this regard, for asubsequent AT or AT OR ABOVE speed constraint, the slope of the portion403 may be determined by constructing a line through the target speed(OPT CLB SPD 2) an the minimum airspeed value that satisfies suchsubsequent speed constraints, thereby minimizing the slope of theportion 403. Prior to reaching the sloped portion 403 with an averagevalue equal to a target speed value, the processing system 106 and/orthe FMS 114 constructs the speed profile 402 with a maximumacceleration, to thereby maximize the duration of the sloped portion 403within the speed envelope region 302. Similarly, for speed enveloperegion 312, in the embodiment of FIG. 4, the processing system 106and/or the FMS 114 constructs a speed profile 404 that accelerates withthe maximum acceleration until reaching a sloped portion 405 configuredto maximize a duration of time that the average climb speed is equal tothe optimum climb speed associated with FL200 (OPT CLB SPD 3) beforereaching the optimum climb speed associated with FL250 (OPT CLB SPD 4)and satisfying the AT OR ABOVE constraint 314.

Referring again to FIG. 2, in accordance with one or more embodiments,the speed profile determination process 200 is iteratively performedacross multiple navigational segments of a procedure to cumulativelymaximize the duration of time when the aircraft is flying at a targetedspeed during the procedure, or alternatively, the duration of time whenthe average speed of the aircraft is equal to a targeted speed. Forexample, navigational segments bounded by AT OR ABOVE or AT OR BELOWspeed constraints have a range of acceptable speeds upon reaching thosewaypoints. Accordingly, the speed profile determination process 200 maybe iteratively performed to increase or decrease speed values at theendpoints of navigational segments (and then update the portion of thespeed profile corresponding to that navigational segment accordingly) toarrive at a solution consisting of sets of speed profiles across themultiple navigational segments that optimizes the aircraft speedrelative to the cost index across execution of the entire procedure. Forexample, a speed profile through the speed envelope region 302 thatstarts at the maximum speed for the AT OR BELOW speed constraint 306rather than OPT CLB SPD 1 may reduce the duration of time the aircrafttravels at (or averages) OPT CLB SPD 1 below FL100 but increase theduration of time the aircraft travels at (or averages) OPT CLB SPD 2,thereby optimizing the aircraft speed across those two segments.Additionally, as described in greater detail below in the context ofFIG. 6, the speed profile determination process 200 could be iterativelyperformed to account for RTA constraints and arrive at an optimal speedprofile that also satisfies RTA constraints in addition to speedconstraints.

Moreover, in some embodiments, the speed profile determination process200 is periodically performed or otherwise updated during flight todynamically update the speed profile as the aircraft travels within anavigational segment, to thereby further optimize the speed profile. Inthis regard, the current aircraft altitude may be treated as the initialnavigational reference point of a navigational segment currently beingflown with the current aircraft speed being treated as an AT speedconstraint associated with that starting point. Thus, as the aircraftdeviates from a previously constructed speed profile, the processingsystem 106 and/or the FMS 114 may dynamically update the speed profileto be used to optimize the speed profile based on the current aircraftstatus.

Referring now to FIG. 5, in accordance with one or more embodiments,speed constraints are padded or relaxed to allow for construction ofspeed profiles that maximize duration of time the aircraft travels at(or averages) a targeted airspeed. For example, AT OR BELOW constraints(e.g., constraint 306) may be padded upward, and AT OR ABOVE constraints(e.g., constraint 314) may be padded downward, while AT constraints(e.g., constraint 304) may be padded upward and/or downward toaccommodate targeted airspeeds while satisfying the speed constraintswithin some threshold margin. In one or more embodiments, theconstraints are padded independently by an amount that is less than orequal to some maximum allowable padding value (e.g., plus or minus 10knots), but the cumulative amount of padding throughout the procedure isequal to zero (e.g., the sum of all upward padding minus the sum of alldownward padding is equal to zero). For example, the AT OR BELOWconstraint 306 may be increased by an amount (PadPos1) to relax thespeeds up its associated waypoint at FL100. The AT constraint 304 may beincreased by a different amount (PadPos2) for purposes of constructingthe minimum travel time boundary 501 for a padded speed envelope region502, while decreased by an amount (PadNeg1) for purposes of constructingthe maximum travel time boundary 503 for the padded speed enveloperegion 502. The AT OR ABOVE constraint 314 may be decreased by adifferent amount (PadNeg2) for purposes of constructing the maximumtravel time boundary 513 for padded speed envelope region 512, while theminimum travel time boundary 511 for the padded speed envelope region512 is constructed using the upwardly padded AT constraint 304 (e.g.,the AT speed constraint plus PadPos2).

In exemplary embodiments, the sum of the positive padding is equal tothe negative padding (e.g., PadPos1+PadPos2=PadNeg1+PadNeg2). Each ofthe padding amounts is less than a maximum allowable padding value(e.g., 10 knots). In one or more embodiments, the padding amounts fordifferent constraints may be different from one another to betteroptimize the cumulative speed profile across the procedure, withoutviolating the maximum allowable padding value and maintaining a netpadding value equal to zero. That said, in some embodiments, the amountof padding may be net positive or net negative to accommodate RTAconstraints, as described in greater detail below in the context of FIG.6.

Still referring to FIG. 5, the speed profile determination process 200may construct speed profiles through the padded speed envelope regionsin a similar manner as described above. In this regard, when the targetspeed for up to FL150 (OPT CLB 2) is greater than the speed valueassociated with the AT constraint 304 (e.g., greater than 270 knots) byless than the maximum padding value, the constructed speed profile 550proceeds with maximum acceleration until reaching the target speedassociated with FL150 and then maintains the airspeed at that OPT CLB 2value to maximize the duration of time at the target speed value withoutincreasing the deviation from the original AT speed constraint 304. Thesubsequent speed profile segment 560 may be constructed with maximumacceleration from the FL150 target speed to the target speed associatedwith FL200 (e.g., OPT CLB 3). By virtue of the padding and increasedspeed at the start of the speed profile segment 560, the target speedassociated with FL200 may be reached sooner, thereby further increasingthe duration of time that the aircraft flies at a targeted airspeedduring the climb.

Referring now to FIG. 6, in accordance with one or more embodiments, thespeed profile determination process 200 is implemented by a speedprofile generator 602 as part of a RTA management system 600 (which maybe implemented by the processing system 106 and/or the FMS 114). Thespeed profile generator 602 receives or otherwise obtains various speedconstraints 601 associated with a procedure (e.g., tasks 202, 204, 206)and generates an initial speed profile 603 based on those speedconstraints and various targeted or desired airspeeds applicable toexecution of the procedure. A trajectory predictor 604 receives thespeed profile output by the speed profile generator 602 and computes oneor more estimated times of arrival (ETAs) 605 based on the speedprofile. The ETAs 605 are provided to an RTA solver 606 which comparesthe ETAs 605 to one or more corresponding RTAs 607 and determines aspeed adjustment 609 based on any differences.

The speed adjustment 609 is then utilized by the speed profile generator602 to adjust the speed profile 603 in a manner that reduces the timedifference (or error) between the ETA(s) 605 and the RTA(s) 607. In thisregard, the speed profile generator 602 may adaptively pad AT or AT ORABOVE speed constraints lower to delay the ETAs 605 in response todownward speed adjustments 609, and conversely, adaptively pad AT or ATOR BELOW speed constraints higher to advance the ETAs 605 in response toupward speed adjustments 609. Additionally, in one or more embodiments,the speed profile generator 602 may vary the manner in which the speedprofile is optimized (e.g., maximizing duration at targeted speedsversus maximizing duration of average speed equal to targeted speeds)based on the requested speed adjustment 609. The updated speed profile603 may then be provided to the trajectory predictor 604 for updatingthe ETAs 605, and so on, to iteratively reduce the speed adjustment 609.

Referring again to FIGS. 1-2, the subject matter described herein allowsfor the processing system 106 and/or the FMS 114 to generate a speedprofile that accounts for speed constraints associated with a procedurewhile also attempting to achieve a desired cost index by accounting fordifferent targeted speeds. For example, multiple different optimum climbspeeds associated with different flight levels (or ranges thereof) maybe accounted for when constructing a speed profile for a departureprocedure having one or more AT or AT OR ABOVE speed constraints. Theresulting speed profile may be utilized by the FMS 114 (or anotherautopilot, autothrottle or flight guidance subsystem) to autonomouslyoperate the aircraft while climbing to best achieve the desired costindex, thereby facilitating cost-efficient operations while attemptingto comply with various speed constraints, RTA constraints, and the like.In various embodiments, the processing system 106 and/or the FMS 114 mayalso generate or otherwise provide a graphical representation of thespeed profile on the display device 102 to thereby allow a pilot tomanually fly the aircraft in a cost effective manner while attempting tomanage aircraft speed and arrival times.

For the sake of brevity, conventional techniques related to autopilot,flight management, route planning and/or navigation, aircraftprocedures, aircraft controls, and other functional aspects of thesystems (and the individual operating components of the systems) may notbe described in detail herein. Furthermore, the connecting lines shownin the various figures contained herein are intended to representexemplary functional relationships and/or physical couplings between thevarious elements. It should be noted that many alternative or additionalfunctional relationships or physical connections may be present in anembodiment of the subject matter.

The subject matter may be described herein in terms of functional and/orlogical block components, and with reference to symbolic representationsof operations, processing tasks, and functions that may be performed byvarious computing components or devices. It should be appreciated thatthe various block components shown in the figures may be realized by anynumber of hardware components configured to perform the specifiedfunctions. For example, an embodiment of a system or a component mayemploy various integrated circuit components, e.g., memory elements,digital signal processing elements, logic elements, look-up tables, orthe like, which may carry out a variety of functions under the controlof one or more microprocessors or other control devices. Furthermore,embodiments of the subject matter described herein can be stored on,encoded on, or otherwise embodied by any suitable non-transitorycomputer-readable medium as computer-executable instructions or datastored thereon that, when executed (e.g., by a processing system),facilitate the processes described above.

The foregoing description refers to elements or nodes or features being“coupled” together. As used herein, unless expressly stated otherwise,“coupled” means that one element/node/feature is directly or indirectlyjoined to (or directly or indirectly communicates with) anotherelement/node/feature, and not necessarily mechanically. Thus, althoughthe drawings may depict one exemplary arrangement of elements,additional intervening elements, devices, features, or components may bepresent in an embodiment of the depicted subject matter. In addition,certain terminology may also be used in the following description forthe purpose of reference only, and thus are not intended to be limiting.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of thesubject matter in any way. Rather, the foregoing detailed descriptionwill provide those skilled in the art with a convenient road map forimplementing an exemplary embodiment of the subject matter. It should beunderstood that various changes may be made in the function andarrangement of elements described in an exemplary embodiment withoutdeparting from the scope of the subject matter as set forth in theappended claims. Accordingly, details of the exemplary embodiments orother limitations described above should not be read into the claimsabsent a clear intention to the contrary.

What is claimed is:
 1. A computer-implemented method of operating avehicle, the method comprising: identifying a first speed constraintassociated with a navigational reference point; determining a speedenvelope region en route to the navigational reference point based atleast in part on the first speed constraint and a maximum accelerationof the vehicle; identifying a target speed en route to the navigationalreference point; determining a speed profile for travel en route to thenavigational reference point within the speed envelope region, whereinthe speed profile intersects the target speed within the speed enveloperegion and a slope of the speed profile is influenced by the targetspeed; and autonomously operating the vehicle in accordance with thespeed profile.
 2. The method of claim 1, further comprising: identifyinga second speed constraint associated with a second navigationalreference point preceding the navigational reference point; identifyinga maximum speed between the navigational reference point and the secondnavigational reference point; and identifying a minimum speed betweenthe navigational reference point and the second navigational referencepoint, wherein determining the speed envelope region comprises:determining a minimum travel time boundary for the speed envelope regionbetween the navigational reference point and the second navigationalreference point based at least in part on the first speed constraint,the second speed constraint, the maximum acceleration of the vehicle,and the maximum speed between the navigational reference point and thesecond navigational reference point; and determining a maximum traveltime boundary for the speed envelope region based at least in part onthe first speed constraint, the second speed constraint, the maximumacceleration of the vehicle, and the minimum speed between thenavigational reference point and the second navigational referencepoint.
 3. The method of claim 2, further comprising padding at least oneof the first speed constraint and the second speed constraint based onthe target speed.
 4. The method of claim 1, wherein the slope of thespeed profile maximizes a duration of time when a speed of the vehicleis equal to the target speed.
 5. The method of claim 1, wherein theslope of the speed profile maximizes a duration of time when an averagespeed of the vehicle is equal to the target speed.
 6. The method ofclaim 1, further comprising identifying a second target speed en routeto the navigational reference point, wherein determining the speedprofile comprises determining the speed profile intersecting the targetspeed and the second target speed within the speed envelope region. 7.The method of claim 6, wherein the slope of the speed profile maximizesa cumulative duration of time a speed of the vehicle is equal to one ofthe target speed and the second target speed.
 8. The method of claim 6,wherein the slope of the speed profile maximizes a duration of time whenan average speed of the vehicle is equal to one of the target speed andthe second target speed.
 9. The method of claim 1, further comprisingdetermining the target speed based on a cost index value.
 10. The methodof claim 1, further comprising: identifying a second speed constraintassociated with a second navigational reference point; determining asecond speed envelope region between the navigational reference pointand the second navigational reference point based at least in part onthe first speed constraint, the second speed constraint, and the maximumacceleration of the vehicle; identifying a second target speed en routeto the second navigational reference point, wherein: determining thespeed profile comprises determining the speed profile for travel fromthe navigational reference point to the second navigational referencepoint within the second speed envelope region; and the speed profileintersects the second target speed within the second speed enveloperegion and a second slope of the speed profile within the second speedenvelope region is influenced by the second target speed.
 11. A methodof operating an aircraft, the method comprising: identifying, by aflight management system (FMS) onboard the aircraft, one of an AT speedconstraint and an AT OR ABOVE speed constraint associated with anavigational reference point of a flight plan; determining, by the FMS,a speed envelope region in advance of the navigational reference pointbased at least in part on a maximum acceleration of the aircraft and theone of the AT speed constraint and the AT OR ABOVE speed constraint;identifying, by the FMS, a target speed en route to the navigationalreference point; determining, by the FMS, a speed profile thatintersects the target speed within the speed envelope region, wherein aslope of the speed profile is influenced by the target speed; andautonomously operating the aircraft in accordance with the speedprofile.
 12. The method of claim 11, wherein determining the speedprofile comprises determining the speed profile that maximizes aduration of time when a speed of the aircraft is equal to the targetspeed.
 13. The method of claim 11, wherein determining the speed profilecomprises determining the speed profile that maximizes a duration oftime when an average speed of the aircraft is equal to the target speed.14. The method of claim 11, wherein determining the speed enveloperegion comprises padding the one of the AT speed constraint and the ATOR ABOVE speed constraint based on the target speed.
 15. The method ofclaim 11, wherein identifying the target speed comprises the FMSdetermining the target speed based on a cost index value and a flightlevel en route to the navigational reference point.
 16. The method ofclaim 11, wherein: identifying the one of the AT speed constraint andthe AT OR ABOVE speed constraint comprises identifying the one of the ATspeed constraint and the AT OR ABOVE speed constraint based on adeparture procedure associated with an airport; and identifying thetarget speed comprises the FMS determining an optimum climb speedassociated with a first flight level below a second flight levelassociated with the navigational reference point based on a cost indexvalue, wherein the speed profile intersects the optimum climb speed. 17.An aircraft system comprising: a data storage element maintainingprocedure information associated with an aircraft action, wherein theprocedure information includes a navigational reference point having aspeed constraint associated therewith; an input device to receive aninput value; and a processing system coupled to the data storage elementand the input device to determine a speed envelope region en route tothe navigational reference point based at least in part on the speedconstraint, identify a target speed corresponding to the input value,determine a speed profile intersecting the target speed within the speedenvelope region, and autonomously operating an aircraft in accordancewith the speed profile, wherein a slope of the speed profile isinfluenced by the target speed.
 18. The aircraft system of claim 17,wherein the slope maximizes a duration of time when a speed of theaircraft is equal to the target speed.
 19. The aircraft system of claim17, wherein the slope maximizes a duration of time when an average speedof the aircraft is equal to the target speed.
 20. The aircraft system ofclaim 17, wherein: the input value comprises a cost index; and thetarget speed is an optimum speed associated with a first flight levelbelow a second flight level associated with the navigational referencepoint.